CVE-2020-10188

CRITICALNVD 9.89.8
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to NVD's CVSS score.

Score 9.8 from GitHub Security Advisory (severity: HIGH) published 2022-05-24. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Elevated

Also known asEUVD-2020-2649 (ENISA EUVD) · GHSA-8239-4cq6-qmwc (GitHub Security Advisories)Source: ENISA EUVD

9.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High exploitation likelihood — EPSS 74%
CISA-KEV: Not listedEPSS PROB: 74%CVSS: 9.8Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

utility.c in telnetd in netkit telnet through 0.17 allows remote attackers to execute arbitrary code via short writes or urgent data, because of a buffer overflow involving the netclear and nextitem functions.

CVSS v3
9.8
EG Score
9.8CRITICALmedium confidence
EG Risk
74
EG Risk 74/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity98% × 45%
Impact severity (EG Severity): CVSS 9.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation74% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's BOD 26-04 default: no one has published Automatable for this CVE, and CISA treats it as “no” for a CVE not in KEV.
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
74%
EPSS %ILE
99th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.8): severity, escalated by confirmed exploitation. This CVE's 9.8 is its impact severity (EG Severity), not escalated.

EG Severity
9.8 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
74% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-11). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

March 6, 2020

Last Modified

January 21, 2026

Advisory Details (9)

Auto-updated Oct 9, 2026
Patch available.
Web page

Telnet Vulnerability Affecting Cisco Products: June 2020

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-telnetd-EFJrEzPx
Web page

[SECURITY] Fedora 30 Update: telnet-0.17-77.fc30 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/K3VJ6V2Z3JRNJOBVHSOPMAC76PSSKG6A/
Web page

[SECURITY] Fedora 32 Update: telnet-0.17-79.fc32 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HLU6FL24BSQQEB2SJC26NLJ2MANQDA7M/
Web page

[SECURITY] Fedora 31 Update: telnet-0.17-78.fc31 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/7FMTRRQTYKWZD2GMXX3GLZV46OLPCLVK/
Web pageMentions a patch (unverified)

[SECURITY] [DLA 2341-1] inetutils security update

https://lists.debian.org/debian-lts-announce/2020/08/msg00038.html
Web pageMentions a patch (unverified)

[SECURITY] [DLA 2176-1] inetutils security update

https://lists.debian.org/debian-lts-announce/2020/05/msg00012.html
Web page

krb5-appl/telnet/telnetd/utility.c at d00cd671dfe945791b33d4f1f6a5c57ae1667ef8 · krb5/krb5-appl · GitHub

https://github.com/krb5/krb5-appl/blob/d00cd671dfe945791b33d4f1f6a5c57ae1667ef8/telnet/telnetd/utility.c#L205-L216
Web page

APPGate Research Blog: BraveStarr – A Fedora 31 netkit telnetd remote exploit

https://appgateresearch.blogspot.com/2020/02/bravestarr-fedora-31-netkit-telnetd_28.html

Vendor Advisories for CVE-2020-10188(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(10)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntuinetutils-telnet (2:1.9.4-1ubuntu0.1~esm1) @ xenial2026-11-12ubuntu
ubuntuinetutils-telnet (2:1.9.4-11ubuntu0.1) @ focal2026-11-12ubuntu
ubuntuinetutils-traceroute (2:1.9.2-1ubuntu0.1~esm2) @ trusty2026-11-12ubuntu
redhattelnet-1:0.17-65.el7_72022-01-18redhat
redhattelnet-1:0.17-65.el7_62022-01-04redhat
redhattelnet-1:0.17-73.el8_0.12020-04-07redhat
redhatkrb5-appl-0:1.0.1-10.el6_102020-04-07redhat
redhattelnet-1:0.17-49.el6_102020-04-06redhat
redhattelnet-1:0.17-73.el8_1.12020-04-06redhat
redhattelnet-1:0.17-65.el7_82020-04-06redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(11 across 6 ecosystems)
Debian:11(3)
PackageVulnerable rangeFix by version rangeDependents
inetutils—
  • every version up to 2:1.9.4-12: fixed in 2:1.9.4-12
—
netkit-telnet—
  • every version up to 0.17-18woody2: fixed in 0.17-18woody2
—
netkit-telnet-ssl—
  • every version up to 0.17.17+0.1-2woody3: fixed in 0.17.17+0.1-2woody3
—
Debian:12(2)
PackageVulnerable rangeFix by version rangeDependents
inetutils—
  • every version up to 2:1.9.4-12: fixed in 2:1.9.4-12
—
netkit-telnet-ssl—
  • every version up to 0.17.17+0.1-2woody3: fixed in 0.17.17+0.1-2woody3
—
Debian:13(2)
PackageVulnerable rangeFix by version rangeDependents
inetutils—
  • every version up to 2:1.9.4-12: fixed in 2:1.9.4-12
—
netkit-telnet-ssl—
  • every version up to 0.17.17+0.1-2woody3: fixed in 0.17.17+0.1-2woody3
—
Debian:14(2)
PackageVulnerable rangeFix by version rangeDependents
inetutils—
  • every version up to 2:1.9.4-12: fixed in 2:1.9.4-12
—
netkit-telnet-ssl—
  • every version up to 0.17.17+0.1-2woody3: fixed in 0.17.17+0.1-2woody3
—
Debian:8(1)
PackageVulnerable rangeFix by version rangeDependents
inetutils2:1.9.2.39.3a460-3
  • every version up to 2:1.9.2.39.3a460-3+deb8u1: fixed in 2:1.9.2.39.3a460-3+deb8u1
—
Debian:9(1)
PackageVulnerable rangeFix by version rangeDependents
inetutils2:1.9.4-2
  • every version up to 2:1.9.4-2+deb9u1: fixed in 2:1.9.4-2+deb9u1
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(10)

Data Freshness Timeline

(refreshed 15× in last 7d / 72× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed its CVE.org record (CNA or CISA ADP). An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 220 rows on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 120 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-12 16:29 UTCEPSS rescoreEPSS 74% · 99th percentile
  2. 2026-11-12 10:59 UTCEchelonGraph re-scored
  3. 2026-11-12 10:59 UTCVendor advisory
  4. 2026-11-12 10:59 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  5. 2026-11-11 16:30 UTCEPSS rescoreEPSS 74% · 99th percentile
  6. 2026-11-11 09:14 UTCEchelonGraph re-scored
  7. 2026-11-11 09:14 UTCVendor advisory
  8. 2026-11-11 09:14 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  9. 2026-11-10 07:30 UTCEchelonGraph re-scored
  10. 2026-11-10 07:30 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  11. 2026-11-09 16:28 UTCEPSS rescoreEPSS 74% · 99th percentile
  12. 2026-11-09 05:46 UTCEchelonGraph re-scored
  13. 2026-11-09 05:46 UTCVendor advisory
  14. 2026-11-09 05:46 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  15. 2026-11-08 04:01 UTCEchelonGraph re-scored
  16. 2026-11-08 04:01 UTCVendor advisory
  17. 2026-11-08 04:01 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  18. 2026-11-07 02:16 UTCEchelonGraph re-scored
  19. 2026-11-07 02:16 UTCVendor advisory
  20. 2026-11-07 02:16 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  21. 2026-11-06 16:29 UTCEPSS rescoreEPSS 74% · 99th percentile
  22. 2026-11-06 00:32 UTCEchelonGraph re-scored
  23. 2026-11-06 00:32 UTCVendor advisory
  24. 2026-11-06 00:32 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  25. 2026-11-05 16:29 UTCEPSS rescoreEPSS 74% · 99th percentile
Show 75 more
  1. 2026-11-04 22:48 UTCEchelonGraph re-scored
  2. 2026-11-04 22:48 UTCVendor advisory
  3. 2026-11-04 22:48 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  4. 2026-11-04 16:29 UTCEPSS rescoreEPSS 74% · 99th percentile
  5. 2026-11-03 21:03 UTCEchelonGraph re-scored
  6. 2026-11-03 21:03 UTCVendor advisory
  7. 2026-11-03 21:03 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  8. 2026-11-03 16:36 UTCEPSS rescoreEPSS 74% · 99th percentile
  9. 2026-11-03 07:25 UTCOSV refresh
  10. 2026-11-02 19:19 UTCEchelonGraph re-scored
  11. 2026-11-02 19:19 UTCVendor advisory
  12. 2026-11-02 19:19 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  13. 2026-11-01 17:27 UTCEchelonGraph re-scored
  14. 2026-11-01 17:27 UTCVendor advisory
  15. 2026-11-01 17:27 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  16. 2026-10-31 16:28 UTCEPSS rescoreEPSS 74% · 99th percentile
  17. 2026-10-31 15:44 UTCEchelonGraph re-scored
  18. 2026-10-31 15:44 UTCVendor advisory
  19. 2026-10-31 15:43 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  20. 2026-10-30 16:29 UTCEPSS rescoreEPSS 74% · 99th percentile
  21. 2026-10-30 13:59 UTCEchelonGraph re-scored
  22. 2026-10-30 13:59 UTCVendor advisory
  23. 2026-10-30 13:59 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  24. 2026-10-29 16:28 UTCEPSS rescoreEPSS 74% · 99th percentile
  25. 2026-10-29 12:15 UTCEchelonGraph re-scored
  26. 2026-10-29 12:15 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  27. 2026-10-28 10:23 UTCEchelonGraph re-scored
  28. 2026-10-28 10:23 UTCVendor advisory
  29. 2026-10-28 10:23 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  30. 2026-10-27 16:27 UTCEPSS rescoreEPSS 74% · 99th percentile
  31. 2026-10-27 07:44 UTCEchelonGraph re-scored
  32. 2026-10-27 07:44 UTCVendor advisory
  33. 2026-10-27 07:44 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  34. 2026-10-26 16:27 UTCEPSS rescoreEPSS 74% · 99th percentile
  35. 2026-10-26 03:24 UTCVendor advisory
  36. 2026-10-26 03:23 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  37. 2026-10-25 18:54 UTCEchelonGraph re-scored
  38. 2026-10-25 16:28 UTCEPSS rescoreEPSS 74% · 99th percentile
  39. 2026-10-25 01:36 UTCEchelonGraph re-scored
  40. 2026-10-25 01:36 UTCVendor advisory
  41. 2026-10-25 01:36 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  42. 2026-10-24 16:28 UTCEPSS rescoreEPSS 74% · 99th percentile
  43. 2026-10-23 23:52 UTCEchelonGraph re-scored
  44. 2026-10-23 23:52 UTCVendor advisory
  45. 2026-10-23 23:52 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  46. 2026-10-22 22:08 UTCEchelonGraph re-scored
  47. 2026-10-22 22:08 UTCVendor advisory
  48. 2026-10-22 22:08 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  49. 2026-10-21 20:12 UTCEchelonGraph re-scored
  50. 2026-10-21 20:12 UTCVendor advisory
  51. 2026-10-21 20:12 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  52. 2026-10-21 16:28 UTCEPSS rescoreEPSS 74% · 99th percentile
  53. 2026-10-20 18:28 UTCEchelonGraph re-scored
  54. 2026-10-20 18:28 UTCVendor advisory
  55. 2026-10-20 18:28 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  56. 2026-10-19 16:41 UTCEchelonGraph re-scored
  57. 2026-10-19 16:41 UTCVendor advisory
  58. 2026-10-19 16:41 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  59. 2026-10-19 16:27 UTCEPSS rescoreEPSS 74% · 99th percentile
  60. 2026-10-18 16:28 UTCEPSS rescoreEPSS 74% · 99th percentile
  61. 2026-10-18 14:51 UTCVendor advisory
  62. 2026-10-18 14:51 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  63. 2026-10-18 09:38 UTCEchelonGraph re-scored
  64. 2026-10-17 13:05 UTCEchelonGraph re-scored
  65. 2026-10-17 13:05 UTCVendor advisory
  66. 2026-10-17 13:05 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  67. 2026-10-16 11:20 UTCEchelonGraph re-scored
  68. 2026-10-16 11:20 UTCVendor advisory
  69. 2026-10-16 11:20 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  70. 2026-10-15 16:27 UTCEPSS rescoreEPSS 74% · 99th percentile
  71. 2026-10-15 09:36 UTCEchelonGraph re-scored
  72. 2026-10-15 09:36 UTCVendor advisory
  73. 2026-10-15 09:36 UTCGHSA enrichmentGHSA-8239-4cq6-qmwc · GitHub severity HIGH · GitHub CVSS 9.8
  74. 2026-10-14 16:28 UTCEPSS rescoreEPSS 74% · 99th percentile
  75. 2026-10-14 05:50 UTCEchelonGraph re-scored

Frequently asked(5)

What is CVE-2020-10188?
CVE-2020-10188 is a critical-severity vulnerability; its CVE record was published on March 6, 2020. utility.c in telnetd in netkit telnet through 0.17 allows remote attackers to execute arbitrary code via short writes or urgent data, because of a buffer overflow involving the netclear and nextitem functions.
When was the CVE record for CVE-2020-10188 published?
The CVE record for CVE-2020-10188 was published on March 6, 2020. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of January 21, 2026; the record at its source may have been updated since.
Is CVE-2020-10188 actively exploited?
CVE-2020-10188 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 74% probability of exploitation in the next 30 days (99th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2020-10188?
CVE-2020-10188 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2020-10188?
A fix for CVE-2020-10188 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2020-10188 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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